Apparatus for and method of manufacturing cores for ignition coils

ABSTRACT

Apparatus for manufacturing laminated cores for spark ignition system ignition coils including a corrugating station which receives sheet metal blanks. Each sheet metal blank has a plurality of parallel slits, which divide the blank into laminae interconnected at their ends. The corrugating station includes a plurality of tools which operate in sequence on the blank to corrugate the blank along the lines of the slits, and the apparatus is such that the undeformed portion of the blank is free to move relative to the tools and the tools sequentially form the corrugations in the blank.

United States Patent 11 1 Wright et al.

[ APPARATUS FOR AND METHOD OF MANUFACTURING CORES FOR IGNITION COILS [75] Inventors: Eric John Wright, Sutton Coldfield;

Desmond Thomas Robinson, Northfield, both of England [73] Assignee: Joseph Lucas (Industries) Limited,

Birmingham, England 221 Filed: Dec. 2, 1971 21 Appl. No.: 204,180

52 U.S. C1 72/382, 72/384, 72/405,

29/2542 [51] Int. CI ..B21d 13/02 [58] Field of Search 72/335, 337, 381, 72/382, 384, 385, 396, 397, 403, 404, 405; 29/2542 [56] References Cited UNITED STATES PATENTS 2,954,068 9/1960 Williamson 72/397 4 2,712,340 7/1955 Sandberg 72/397 2,510,024 5/1950 Mayer 72/397 1,431,175 10/1922 Ogden et a1. 72/404 2,991,540 7/1961 Gaut 29/2542 FOREIGN PATENTS OR APPLICATIONS 333,340 8/1930 Great Britain 72/396 Primary Examiner-L0well A. Larson At!0rneyH0lman & Stern [57] ABSTRACT Apparatus for manufacturing laminated cores for spark ignition system ignition coils including a corrugating station which receives sheet metal blanks. Each sheet metal blank has a plurality of parallel slits, which divide the blank into laminae interconnected at their ends. The corrugating station includes a plurality of tools which operate in sequence on the blank to corrugate the blank along the lines of the slits, and the apparatus is such that the undeformed portion of the blank is free to move relative to the tools and the tools sequentially form the corrugations in the blank.

25 Claims, 19 Drawing Figures PATENTEU DU 2 7 sum 01 0F 13 PATENTEI] URI 2 I975 SHEET 02 0F 13 PATENTEU 2|973 3.762.206

' sum over 13 PAIENTED 2|975 3.762.206

saw us or 13 PATENTED 2 7 sum 10 or 1 II III U APPARATUS FOR AND METHOD OF MANUFACTURING CORES FOR IGNITION COILS This invention relates to apparatus for and a method of, manufacturing laminated cores for spark ignition system ignition coils.

Apparatus according to the invention includes a corrugating station which receives sheet metal blanks each of which has a plurality of parallel slits dividing the blank into a plurality of laminae interconnedted at their ends, the corrugating station including a plurality of tools which operate sequentially to corrugate a blank along the lines of the slits, the undeformed portion of the blank being free to move relative to the tools as the tools sequentially form the corrugations.

Preferably said tools each include a punch and an anvi], the punches being movable towards and away from the anvils and being movable relative to one another and the anvils being movable relative to one another, the relative movement between the punches and the relative movement between the anvils effecting the sequential formation of the corrugations.

Conveniently the unches are carried by the movable platen of a press and move therewith, the punches being urged to predetermined positions relative to one another by resilient means and collapsing in turn relative to one another against the action of said resilient means during a single power stroke of the press, to provide a sequential action. Preferably the punch of the last tool is fixed relative to the movable platen.

Desirably said resilient means is constituted by compressed air.

Desirably the anvils are carried by the fixed platen of the press and are relatively movable in a direction at right angles to the direction of movement of the punches.

Conveniently the anvil which is utilized first in the sequence is fixed relative to the fixed platen and the remaining anvils are movable towards and away from the fixed anvil.

Preferably the movable anvils are moved towards the fixed anvil to their operative positions in response to movement of the movable platen towards the fixed platen, preferably by cams carried by the movable platen so that the movement of the anvils is timed to occur in relation to the movement of the punches.

Desirably the corrugating station includes at least two stages which operate simultaneously, each stage including a set of said tools and the tools of the first stage producing a first set of corrugations in a blank while the second stage produces a second set of corrugations in a blank previously operated on by the first stage, the apparatus including first transfer means for transferring blanks from the first stage to the second stage.

Preferably a centre corrugation of the blank is formed first and the tools operate sequentially, outwardly from the centre corrugation to produce the remaining corrugations, the ourter undeformed portions of the blank being free to move inwardly as the corrugations are formed.

Desirably the apparatus further includes a coining station operated by the movement of the movable platen of the press, the coining station receiving a corrugated blank from the corrugating station and compressing the corrugated blank laterally, at right angles to the corrugations, to form an unfinished laminated core, the apparatus including second transfer means for transferring corrugated blanks to the coining station.

Preferably the coining station includes a pair of plungers which are slidable towards and away from one another between a pair of fixed parts, and said transfer means delivers the corrugated blank between said fixed parts and between said plungers, said fixed parts resisting bowing of the corrugated blank out of the plane of movement of the plungers as the plunger move toward one another to compress the corrugated blank.

Conveniently the coining station includes stripping means which ensures that the unfinished core disengages from the plungers as the plungers move apart.

Desirably the apparatus further includes a sizing station, and third transfer means for transferring unfinished cores from the coining station to the sizing station where the unfinished cores are subject to a sizing operation.

Conveniently the sizing station includes a sizing die through which the unfinished cores are pushed. Preferably the force required to push the unfinished cores through the sizing die is derived from the movement of the movable platen of the press.

Desirably the sizing station includes indexing means operated by movement of the movable platen of the press for indexing unfinished cores through from a position perpendicular to the direction of movement of the movableplaten to a position in line with said direction of movement.

Desirably the apparatus still further includes a blank forming station from which blanks are supplied to the corrugating station.

Conveniently the blank forming station receives a continuous strip of metal said strip being fed to the blank forming station in a step wise manner such that for each complete stroke of the press a length of strip equal in length to the length of the core to be produced is fed into the station.

Desirably the blank forming station includes a slitting tool which for each stroke of the press produces the necessary slits in a length of strip which will constitute a single blank.

More desirably the blank forming station further includes a planishing tool which for ech stroke of the press planishes a previously slitted length of the strip.

Conveniently the blank forming station still further includes a guillotine which cuts previously slitted and planished lengths of strip to form blanks.

Preferably the blank forming station is provided with a cropping tool which crops the edges of the incoming strip prior to the slitting operation, to ensure the width of the strip and therefore the width of the blanks to be formed is the desired width and to ensure that the edges of the strip are correctly orientated relative to the slitting tool.

Advantageously the apparatus includes fourth transfer means for feeding blanks from the blank forming station to the corrugating station.

Desirably said first, second and third, and fourth transfer means are part of a movable carriage and operate simultaneously, said carriage being moved in conjunction with the movable platen of the press and being moved in a direction to feed components by an air spring which is compressed by the drive mechanism of the press to move the carriage in a return direction.

Desirably the core to be produced is cylindrical, the slits in the blank being spaced apart by descreasing amounts on either side of the centre line of the blank so that the laminae defined between-the slits decrease in width progressively from the central laminae towards the outermost laminae, the widths of the laminae decreasing in such a manner that when the corrugated blank is coined then the unfinished core is generally cylindrical, the sizing die through which the unfinished cores are passed rendering the cores more accurately cylindrical.

A method according to the invention includes the steps of supporting a sheet metal blank on a fixed anvil which comprises a pair of ribs of triangular cross section defining between them a V-shaped groove, the blank being supported with a slit therein aligned with the apex of the groove, moving a punch of triangular cross section towards the anvil so that the punch engages the blank along the line of said slit and deforms the blank into said groove to form a first corrugation, the uncorrugated portion of the blank being free to move inwardly as the corrugation is formed, moving a second punch of triangular cross section towards the blank along side the first punch and moving a second anvil of triangular cross section towards the first anvil, the second and first anvils when interengaged defining a second V-shaped groove parallel to said first V- shaped groove the second punch bending the blank along the line of a second slit into said second V-shaped groove, as said second V-shaped groove is formed, to form a second corrugation in the blank, forming the required number of corrugations in the blank in similar manner, and compressing the corrugated blank transversely of the corrugations to collapse the blank so that the corrugations lie in facial contact.

Preferably as the second punch and second anvil are being moved to form the second corrugation, a third punch and a third anvil are moved to form a third corrugation on the opposite side of the first corrugation.

Preferably all of the corrugations with the exception of the first are produced in pairs, the corrugations of each pair being on opposite sides respectively of the central corrugation, and the corrugations being produced sequentially in a direction outwardly from the first corrugation.

One example of the invention is illustrated in the accompanying drawings wherein:

FIG. 1 is a front elevational view of a machine for forming cores for ignition coils,

FIG. 2 is a plan view of the machine shown in FIG. 1, with the upper part of the machine removed for clary,

FIGS. 3 and 4 are sectional views illustrating two operative positions of a part of the machine shown in FIG.

FIG. 5 is a plan view of a blank,

FIGS. 6 and 7 show respectively two operative positions of a first part of a corrugating stage of the machine shown in FIG. 1, FIGS. 6 and 7 showing only half of the stage, the remaining half being substantially a mirror image of the half shown,

FIG. 8 is a sectional view on the line 8-8 in FIG. 7,

FIG. 9 is a sectional view of a component of the corrugating stage shown in part in FIG. 7,

FIG. 10 is a diagrammatic representation, to an enlarged scale of the operation of part of the corrugating stage shown in FIG. 7,

FIGS. .11 and 12 respectively are views similar to FIGS. 6 and 7, but showing a second stage of the corrugating station of the machine, I

I FIGS. 13 and 14 respectively are views similar to FIGS. 6 and 7 but showing a third stage of the corrugating station of the machine,

FIG. 15 is a diagrammatic representation of the component produced by the corrugating station of the machine,

FIGS. 16 and 17 respectively are sectional views illustrating two operative positions of a coining station of the machine,

FIG. 18 is a sectional view of a sizing station of the machine, and

FIG. 19 is a sectional view on the line 19-19 in FIG. 18.

Referring to the drawings the machine includes a fixed platen 11 and a movable platen l2 movable towards and away from the fixed platen 11. A crank mechanism (not shown) of a form known in the press art is provided for moving the platen 12 towards and away from the platen 11. The machine includes several operating stations each of which derives its operating power from the movement of the platen 12. At one end of the machine is disposed a blank forming station 13 which receives a continuous strip 14 of mild steel both faces of which are coated with an insulating varnish. Blanks produced by the station 13 are transferred to a corrugating station 15, and blanks corrugated by the station 15 are transferred to a coining station 16. The coining station produces unfinished ignition coil cores, which are then transferred to a sizing station 17. The sizing station finishes the cores, and delivers them into a transfer chute 18 by means of which the finished cores leave the machine.

The blank forming station receives the mild steel strip 14, which is driven into the machine in a stepwise manner from a roll of strip stored at one end of the machine. The mechanism for feeding strip 14 into the machine is operated by the reciprocating movement of the platen l2, and for each complete stroke of the platen 12, that is to say a movement of the platen 12 from its fully raised position, through its fully lowered position and back to its fully raised position, a length of strip equal in length to the core which is to be produced is fed into the machine. The blank forming station includes a cropping tool having a pair of cutters 21 carried by the platen 12, which co-act with corresponding cutters (not shown) on the fixed platen 11. The cutters 21 are spaced apart by a distance equal to the desired width of a blank to be produced, and the length of each of the cutters 21 is equal to the length of the blank to be produced. Thus, the cutters 21 operate on the incoming strip 14 to ensure that the strip 14 is of the desired width, and also to ensure that the lateral edges of the incoming strip are in the desired orientation with respect to succeeding tools of the blank forming station. Assuming that the sequence starts with the platen 12 in its lowermost position, then as the platen 12 is raised a predetermined length of strip 14 is fed between the movable cutters 21 and the fixed cutters of the cropping tool. As the platen 12 reaches its uppermost position, and once again starts to descent towards the platen ll feeding of the strip 14 ceases, and the predetermined length of strip 14 is cropped by the cutters 21. The platen 12 then starts to move away from the platen 11, and a further length of strip 14 is fed into the cropping tool. As the further lengths of strip 14 is fed into the cropping tool the previously cropped length is fed between the fixed and movable parts of a slitting tool 22. The slitting tool includes a plurality of punches which are of rectangular cross-section, and the lengths of which are slightly less than the length of the core which is to be produced. As will be explained later, the core which is to be produced is cylindrical, and so the punches of the slitting tool are not all of the same width. The punches decrease in width from the longitudinal centre line of the tool, towards the lateral edges of the tool, the widest punches being adjacent the centre line of the tool. Moreover, the spacing between the punches decreases in a similar manner. The punches are carried by the movable platen 12 of the press, and the fixed platen carries a part having recesses aligned with the punches. As the movable platen descends towards the fixed platen the punches perform a shearing operation on the strip, and each punch produces a pair of longitudinally extending slits in the strip 14. As stated above, the punches are slightly shorter in length than the length of the portion of the strip which has been fed into the slitting tool, and so this portion of the strip has an unslitted region at both ends. By virtue of the sizing and spacing of the punches of the slitting tool the spacing between the slits formed in the strip decreases towards the lateral edges of the strip. The action of the slitting tool is essentially a shearing action, and so leaves the strip with alternate regions between the slits deformed downwardly out of the plane of the remainder of the strip. It will be appreciated that as the slitting tool is operating on one length of strip then the cropping tool will be operating on a following length of strip. As the platen 12 once again moves away from the fixed platen 11 the strip 14 is once again fed into the machine, and so the slitted length of the strip 14 is moved out of the slitting tool, and into a planishing tool 23. The planishing tool includes a pair of flat plates one of which is carried by the movable platen and the other of which is carried by the fixed platen. The width of the plates is greater than the width of the strip, and the length of the plates is substantially equal to the length of the core which is to be produced. As the platen 12 once again descends towards the platen 11 the planishing too] flattens the slitted strip to render the slitted strip substantially planar. It will be appreciated that as the slitted length of strip is being planished then further lengths of strip are simultaneously being slitted and cropped by the preceding tools. Subsequent raising of the platen 12 once again feeds a further length of strip into the machine, and thereby moves the planished length of strip to a guillotine 24. The guillotine 24 (FIG. 3) includes a movable blade 25 carried by the platen l2 and a fixed blade 26 carried by the platen 11. The strip 14 is fed beyond the edge of the fixed blade' 26 by an amount equal to the length of the core to be produced, and the free end of the strip 14 remote from the tool 26 is supported by a latch 27. The latch 27 is pivotally mounted on an extension 28 of the fixed platen 11, and is spring urged to a position wherein it supports the free end of the strip 14 above the fixed platen. The movable part of the latch 27 is provided with a cam surface 29 engageable by a cam form 31 carried by the movable platen 12. Thus as the movable platen 12 descends, the tool 25 severs the projecting length of strip 14 from the remainder of the strip 14, and at the same time the cam form 31 releases the latch 27 from the strip 14 to permit the severed portion of the strip 14 to drop relative to the blade 26. The severed length of the strip 14 now constitutes a blank to be fed to the corrugating station 15.

The blank 32 (FIG. 5) is of length equal to the length of the core which it is desired to produce, and has a plurality of longitudinally extending slits therein which divide the blank 32 into a plurality of laminae 33 interconnected at each end by unslitted regions 34. The width of the laminae 33 are such that when the blank 32 is subsequently corrugated along the lines of the slits, and then compressed, then the resultant unfinished core will be of substantially cylindrical configuration.

The blank 32, cut form the strip 14, drops onto the fixed platen ll of the machine, and is transferred by a transfer mechanism to the corrugating station, 15. An air blast ensures that the blank does not adhere to the guillotine blade.

The transfer mechanism which transfers the blank through the three stages of the corrugating station, and subsequently through the coining station consists of a carriage 35 which is reciprocable longitudinally of the fixed platen 11. The carriage consists of a pair of cylindrical rods 36, 37 which are guided for longitudinal sliding movement relative to the platen 11 in bearing carried by the platen 11. At their ends remote from the strip input the rods 36, 37 are provided with splined regions 36a, 37a passing through respective internally splined sleeves 38, 39. The internally splined sleeves are coupled to a linkage (not shown) whereby the sleeves, and therefore the rods 36, 37 can be caused to rotate through a predetermined angular distance. The sleeves are coupled to respective levers which in turn act on respective air springs 41, the air springs 41 urging the sleeves, and therefore therods 36, 37 to rotate back to their original angular positions. The rotational-reciprocatory movement of the rods 36, 37 is controlled by a cam mechanism, which times the rotational reciprocatory movement of the rods in accordance with the position of the platen 12.

The ends 36a, 37a of the rods 36, 37 are interconnected by a bridge piece 42 within which the ends of the rods 36, 37 are rotatably mounted. The bridge piece 42 is connected by way of a cam operated linkage to the crank mechanism driving the platen 12, in such a manner that for a complete stroke of the platen 12, the carriage 35 goes through a complete reciprocating stroke in a direction longitudinally of the fixed platen 11. Thus as the movable platen l2 performs a single stroke, then the carriage 35 performs a single reciprocating stroke, longitudinally of the machinewhile the rods 36, 37 also perform a rotary reciprocating stroke, the rods 36, 37 being rotated in opposite angular directions.

The cam operated linkage coupling the bridge piece 42 to the crank mechanism of the press includes an air spring, which opposes movement of the linkage in a direction to move the carriage towards the blank forming station. The carriage is moved positively in this direction by a rotatable cam on the drive of the press thereby compressing the air spring. However the movement of the carriage in a feed direction is caused by restoration of the air spring so that in the event that the transfer mechanism becomes jammed, then restoration of the air spring is prevented by the jamming so that the crank mechanism of the press continues to operate,

without moving the transfer mechanism in a direction to feed components through the machine. An electrical counting arrangement is provided in the machine, which senses complete strokes of operation of the transfer mechanism. In the event that the transfer mechanism does not complete a full stroke then the counting system initiates means for switching off the machine. It will be appreciated that in the event of a component jamming within the machine, and preventing operation of the transfer mechanism, then the machine will switch itself off, thereby minimising the risk of damage to the machine.

The transfer mechanism further includes a pair of arms 43 which are located beneath the blank 32 when the blank 32 is severed from the strip 14. The severed blank 32 falls onto, the arms 43, and as the platen 12 starts to move away from the platen 11 after severing the blank from the strip, the carriage 35 is moved longitudinally of the machine in a direction towards the strip 14. The arms 43 move with the carriage, and so slide under the severed blank 32. The arms 43 clear the rear edge of the blank and permit the blank to fall fully onto the fixed platen with the arms 43 to the rear of the blank. The arms 43 are mounted on the rods 36, 37 in such a manner that the arms move axially but not angularly with the rods. Before the movable platen 12 reaches its limit of movement away from the fixed platen 11, the carriage 35 is moved in a direction away from the blank forming station under the action of said air spring and so moves the blank into the corrugating station. The movement of the carriage 35 in a feed direction is completed during the initial downward movement of the platen l2 and so the arms 43 are positioned in readiness to receive a further blank guillotined from the strip 14.

The corrugating station is formed in three longitudinally spaced stages for convenience, the operation of the three stages being substantially identical.

The first stage 45 of the corrugating station (FIGS. 6, land 8) includes three sequentially operable tools including punches and anvils. A first anvil 46 (FIG. 9) is affixed to the platen 11, the first anvil defining a pair of longitudinally extending ribs 47, 48 of triangular cross-section the ribs 47, 48 defining between them a longitudinally extending V-shaped groove 49. The anvil 46 extends longitudinally of the machine, and the length of the anvil 46 is slightly in excess of the length of the blank 32, that is to say slightly in excess of the length of the core which it is desired to produce. Positioned on opposite sides of the anvil 46 are a second anvil 51 and a third anvil (not shown) the second and third anvils each define a longitudinally extending rib of triangularcross-section, and the lengths of the second and third anvils are equal to the length of the anvil 46. The second and third anvils are normally spaced outwardly from the first anvil, but are movable, as will be described later, to engage the first anvil. When engaged with the first anvil, the second and third anvils define respective V-shaped grooves on opposite sides of the V-shaped groove 49. On opposite sides of the second and third anvils respectively are a fourth anvil 52 and a fifth anvil (not shown). The fourth and fifth anvils are equal in length to the first, second and third anvils, and the fourth and fifth anvils are also movable towards and away from the first anvil. The fourth and fifth anvils do not define triangular ribs, the fourth and fifth anvils having a flat upper surface, and chamfered surface which is presented to the second and third anvils respectively. Thus when the fourth and fifth anvils engage the second and third anvils respectively, then the charnfered surfaces of the fourth and fifth anvils define with the second and third anvils respective V- shaped grooves between the second and fourth anvils and the third and fifth anvils respectively. The first stage 45 further includes a punch assembly 53 carried by the movable platen 12. The punch assembly is in three sections, a first section 54 carrying a first punch 55, a second section 56 carrying a second punch 57 and a third punch (not shown) the second and third punches being disposed on opposite sides respectively of the first punch, and a third section 58 carrying a fourth punch 59 and a fifth punch (not shown), the fourth and fifth punches being disposed on opposite respectively of the assembly defined by the first, second and third punches.

The third section 58 is fixedly secured to the platen l2, and defines a cylinder within which the second section 56 is movable, the second section 56 constituting a piston, and sealing rings being disposed in grooves of the outer surface of the section 56, and engaging the inner surface of the section 58. The section 56 also defines a cylinder, within which is movable the section 54. The section 54 also constitutes a piston, and is provided with sealing rings. Compressed airis admitted to a chamber 61 by way of an inlet passage 62 in the section 58. The ends of the sections 54 and 56 form one wall of the chamber 61, and so the sections 54, 56 are urged to move downwardly relative to the platen l2 and the section 58. Abutment surfaces 63 are provided on the sections 56 and 58 to limit the downward movement of the section 56 relative to the section 58, and similar abutment surfaces 64 are provided on the sections 56 and 54 to limit the downward movement of the section 54 relative to the section 56. Thus when the platen 12 is in a raised position then the first punch 55 projects below the second and third punches, and the second and third punches in turn project below the fourth and fifth punches. It will be appreciated that the first punch can collapse relative to the second and third punches, and moreover the first, second and third punches can collapse relative to the fourth and fifth punches, the collapse of the punches taking place in a direction towards the platen 12, and taking place against the resilient action of the compressed air.

Each of the five punches defines a longitudinally extending triangular rib the length of which is slightly greater than the length of the blank 32, and the apices of the ribs being presented towards the anvils of the first stage. The apex of the punch 55 is accurately aligned with the apex of the groove 49 in the first anvil 46, and similarly the apices of the second, third fourth and fifth punches are accurately aligned with the apices of the V-shaped grooves defined by the first, second, third, fourth and fifth anvils, when the anvils are moved into contact with one another.

The blank 32 is delivered to the first stage of the station 15 by the arms 43, and is guided in its movement intothe first stage so that the blank 32 is positioned accurately between the anvils and the punches. The blank 32 has 25 longitudinally extending slits therein, and the centre first slit is accurately aligned with the apex of the punch 55, and the apex of the groove 49, that is to say the apex of the groove 49, the centre slit of the blank 32, and the apex of the punch 55, all lie in a common plane extending longitudinally of the blank 32, and parallel to the direction of movement of the platen 12. As stated above, the blank 32 is positioned in the first stage as the platen 12 reaches its uppermost position. As the platen 12 starts to descend, the punch 55 is closer to the blank 32 than the remaining punches, and the second, third, fourth and fifth anvils are retracted from the first anvil. The punch 55 engages the blank 32, accurately along the line of the centre slit in the blank, and bends the blank into the groove 49 in the first anvil 46. As the punch 55 pushes the central region of the blank into the groove 49, the blank bends along the line of the central slit therein, and the portions of the blank 32 on opposite sides of the anvil 46 are drawn inwardly. When the central region of the blank 32 is bent completely into the groove 49, the punch 55 is of course arrested. However, the platen 12 at this stage has not reached its lowest position, and so continues to move towards the platen 11. Thus the punch 55 begins to collapse into the punch assembly, against the resilient action of the compressed air in the chamber 61. The dimensions of the anvil 46 and the punch 55 are such that when the central region of the blank 32 has been fully moved into the groove 49, then the slits adjacent to the central slit of the blanks, and on opposite sides thereof, are aligned with the apices of the ribs 47, 48 of the anvil 46.

As the punch 55 begins to collapse into the punch assembly, the second and third punches engage the blank outwardly from the second and third slits,and so commence to bend the blank about the lines of the second and third slits. At this stage, the V-shaped grooves on opposite sides of the groove 49 have not yet been formed, since the second and third anvils are still spaced from the first anvil, on opposite sides thereof. The second and third anvils now commence to move towards the first anvil in the following manner. The second anvil is mounted at one end of a pair of push rods 65 which at their opposite ends carry cam followers 66 engageable by cams 67 carried by the movable platen 12. The rods 65 are mounted for sliding movement in an anvil supporting body 68 fixed to the platen 11, and the cams 67 and cam followers 66 are so arranged that as the second and third punches commence to bend the blank, then the second and third anvils are moved towards the first anvil. The arrangement is such that during this movement both the second and third punches, and the second and third anvils perform a bending action on the regions of the blank between the first and second anvils, and the first and third anvils respectively. The cams 67 and cam followers 66 are so arranged that the second and third anvils engage the first -anvil as the second and third punches complete their travel. Thus, the blank is simultaneously bent along the lines of the second and third slits and the fourth and fifth slits. As the bending takes place, the regions of the blank on opposite sides of the region which is being bent are drawn inwardly. The third anvil is moved by cams, cam followers, and a push rod simultaneously and in the same manner as the second anvil.

When the regions of the blank have been bent completely into the grooves defined by the first and second, and first and third anvils, then the second and third punches cannot move any further towards the platen 11. However, the platen 12 has still not reached its lower most position, and continues to move towards the platen 11. Thus the fourth and fifth punches are brought into engagement with the blank, and commence to bend the blank along thelines of the sixth and seventh slits, the sixth and seventh slits being at this time aligned with the apices of the triangular ribs of the second and third anvils. As the fourth and fifth punches commence to bend the blank the fourth and fifth anvils commence to move towards the second and third anvils respectively. The fourth anvil is also mounted at the end of a pair of push rods 69 slidably mounted in the body 68, the opposite ends of the push rods 69 being connected to a cam follower 71 engageable by a cam form 72 carried by the platen 12. It will be appreciated, that the third and fifth anvils are moved in a manner identical to that described with reference to the second and fourth anvils, and simultaneously therewith, the machine including push rods, cam followers and cam forms associated with the third and fifth anvils, and identical in form and operation to that described with reference to the second and fourth anvils. Thus the blank is bent about the sixth and seventh, and eighth and ninth slits simultaneously as the fourth and fifth anvils move towards the second and third anvils, and the fourth and fifth punches move towards the anvils. As stated above, the fourth and fifth anvils do not define triangular ribs, but have fiat top surfaces. Similarly, the fourth and fifth punches have flat surface positioned outwardly from their respective triangular ribs. Thus as the fourth and fifth punches complete their movement then the blank is also bent about the tenth and eleventh slits, the blank being bent about the tenth and eleventh slits to a position wherein the outer, uncorrugated regions of the blank are co-planar. The fourth and fifth punches are arrested when the platen 12 achieves its lower most position. Thereafter, the platen 12 starts to move away from the platen 11, thereby lifting the punch assembly 53 away from the anvil assembly. Since the first, second and third punches are urged downwardly by compressed air, as described above, when as the punch assembly 53 retracts from the anvil assembly the fourth and fifth punches will disengage from the blank prior to the second and third punches, and similarly the second and third punches will be disengaged from the blank prior to disengagement of the first punch. The cam forms 67 and 72 disengage from their respective cam followers 66, 71 in a similar manner, but disengagement of the cam forms from the cam followers does not retract the anvils. Thus although the punches disengage from the blank, and return to their original positions relative to one another, the anvils at this stage remain in a closed configuration. Clearly, since the partially corrugated blank is engaged with the anvils, and follows the grooves defined by the anvils, then retracting the anvils to their open configuration would damage the corrugated portion of the blank.

The transfer mechanism is provided with a further pair of transfer arms 74 clamped to the rods 36, 37 respectively. The arms 74 move longitudinally in a manner identical to the arms 43 but also move angularly with the rods 36, 37. The arms 74 are positioned in front of the blank'32 when the blank 32 has been initially moved into the first stage of the corrugating station. As the platen 12 reaches the limit of its movement towards the platen 11, to corrugate the blank the arms 74 start to lift as the rods 36, 37 are rotated. The arms, in a lifted positon, then move towards the blank forming station and before the platen 12 reaches its upward limit the arms are lowered to engage behind the partly corrugated blank. The arms 74 then are moved in the opposite direction and transfer the partly corrugated blank to the second stage of the corrugating station, while the arms 43 move a further blank into the first stage. Co-cxtensive with the first anvil, and extending throughout the length of the corrugating station, through all three stages, is a guide rail, the upper surface of which conforms to the shape of the first anvil. As a partly corrugated blank is pushed from the first stage into the second stage, the blank is maintained in the desired orientation relative to the remainder of the machine by the guide rail.

When a partly corrugated blank has been moved out of engagement with the anvils of the first stage, then the anvils can be returned to their original positions in readiness for a further cycle of operation. The second and fourth anvils are returned to their original positions by means of a pneumatically operated ram 75 the piston of which is coupled to a push rod 75a mounted for sliding movement in a passage in the anvil support member 68. At its end remote from the ram 75 the push rod 75a carries a finger 76 engageable with the second anvil. Operation of the ram withdraws the piston thereof, thereby pulling the rod 75a and consequently the second and fourth anvils towards the ram, thereby returning the second and fourth anvils and their associated cam followers to their original positions in readiness for the further cycle of operation. The third and fifth anvils are returned to their original positions in an identical manner by a second ram 77. The rams 75, 77 are operated simultaneously, so that both the second and fourth, and the third and fifth anvils are returned at the same time. The operation of the rams 75, 77 is timed by a cam control mechanism which ensures that the anvils are not returned to their original positions until the transfer arms 74 have moved the blank out of engagement with the anvils. After the anvils have been retracted the cam control mechanism causes operation of the rams 75, 77 in the opposite direction, to return the finger 76, and the finger associated with the ram '77 to their original positions.

The second stage 78 of the corrugating station is extremely similar to the first stage described above. The anvil assembly includes a first anvil 81 which is fixed relative to the platen 11, and which defines a pair of triangular ribs one of which is shown at 82. The two triangular ribs are spaced on opposite sides of the longitudinal centre line of the corrugating station, and between the two ribs the first anvil is provided with a pair of triangular ribs which constitute extensions of the first anvil of the first station, and which locate the partly corrugated blanks in the correct position in the second stage. Positioned on one side of the anvil 81 are second and fourth anvils 83, 84 similar to the second and fourth anvils of the first station, although of smaller dimension. The second and fourth anvils 82, 84 are movable towards the anvil 81 through the intermediary of push rods, cam followers, and cam forms exactly in the manner described in the first stage. On the opposite side of the anvil 81 are disposed third and fifth anvils, also movable in the manner described with reference to the first stage. A pair of rams 85, 86 (FIG. 2) are operable simultaneously with the rams 75, 77 to return the anvils to their original positions. The punch assembly 87 of the second stage is similar to the punch assembly 53 of the first stage, and includes a first section 88 carrying a first punch 89 and a second punch (not shown),

a second section 91 carrying a third punch 92 and fourth punch (not shown) and a third section 93 fixed to the movable platen l2 and carrying a fifth punch 94 and a sixth punch (not shown). The first and second punches are spaced apart on opposite sides of the longitudinal centre line of the corrugating station, and are collapsible into the third and fourth punches against the resilience of compressed air as described with reference to the first stage. The third and fourth punches are spaced on opposite sides of the first and second punches, and are collapsible relative to the fifth and sixth punches also against the resilience of compressed air.

When the partially corrugated blank is engaged in the second station, then the centre corrugations are engaged on the ribs of the first anvil which constitute extensions of the first anvil, thereby locating the blank in the correct position. lnthis position, the tenth and eleventh slits of the blank, which it will be recalled where the last slits along which any bending took place in the first stage, should be aligned with the apices of the ribs of the first anvil. The first and second punches of the second station are arranged to engage the laminae defined between the eighth and tenth slits, and between the ninth and eleventh slits respectively, to ensure that the tenth and eleventh slits do coincide with the apices of the ribs of the first anvil. Thus the first and second punches do not necessarily perform any bending action on the blank, assuming that the blank has not stretched or contracted during its transfer from the first station. However, it is desirable to ensure that the tenth and eleventh slits do in fact coincide with the apices of the ribs of the first anvil in order to minimise the effects of tolerance build-up across the width of the blank.

The operation of the second stage of the corrugating station after the first and second punches have ceased to move is identical with that described in relation to the first stage, and after the blank has been bent along the lines of the tenth twelfth, fourteenth, sixteenth, and eighteenth slits by the third and fifth punches and the second and fourth anvils, and along the lines of the eleventh, thirteenth, fifteenth, seventeenth, and ninteenth slits by the fourth and sixth punches, and the third an fifth anvils, the movable platen 12 once again starts to move away from the platen 11. A further pair of transfer arms 95 clamped to the rods 36, 37 operate simultaneously with the transfer arms 74, to move the partly corrugated blank from the second corrugating stage, into the third corrugating stage, while the arms 74 transfer a blank partly corrugated in the first stage, to the second stage, and while the arms 43 transfer an uncorrugated blank to the first stage.

The third stage 97 of the corrugating station 15 is similar in its operation to the previous two stages, and includes an anvil assembly having a first anvil fixed relative to the platen 11 and defining a first triangular rib 98 and a second traingular rib (not shown). The two ribs of the first anvil are spaced on opposite sides of the longitudinal centre line of the corrugating station, and the first anvil also defines a centrally disposed pair of triangular ribs which constitute guide rail extensions of the triangular ribs of the first anvil of the first stage. Second and fourth anvils are positioned on one side of the first anvil, adjacent the rib 98, and are movable towards and away from the rib 98 of the first anvil in a manner identical with that described with reference to the first stage of the corrugating station. Similarly, third 

1. Apparatus for use in the manufacture of laminated cores for spark ignition system ignition coils, including a corrugating station which receives sheet metal blanks each of which has a plurality of parallel slits spaced apart by different distances dividing the blank into a plurality of laminae of different widths interconnected at their ends, the corrugating station including a movable platen movable relatively towards and away from a fixed platen, a plurality of punches carried by the movable platen and moving therewith, resilient means urging the punches to predetermined positions relative to one another and to the movable platen, the punches being mounted for collapsing movement in the direction of the stroke of the movable platen in turn relative to one another and to the movable platen against the action of said resilient means during a single operating stroke of the movable platen so that the punches can collapse relative to one another in sequence during said single operating stroke, a plurality of anvils associated with said punches and carried by the fixed platen, the anvil associated with the first punch of said plurality of punches being fixed, and the remaining anvils being movable laterally with respect to the direction of movement of the movable platen, relative to one another, in sequence, towards and away from the fixed anvil and, means operated by the movement of the movable platen causing movement of the movable anvils towards the fixed anvil in a sequential manner determined by the movement of the movable platen towards the fixed platen, so that the movement of the anvils is timed in a predetermined relation to the movement of the punches, the relative movement between the punches and the relative movement between the anvils, together with the relative movement of the punches with respect to the anvils effecting a sequential formation of corrugations in said blank, with said slits at the apices of the corrugations.
 2. Apparatus as claimed in claim 1 wherein said resilient means is constituted by compressed air.
 3. Apparatus as claimed in claim 1 wherein said movement of the movable anvils is effected by cams carried by the movable platen.
 4. Apparatus as claimed in claim 1 wherein the corrugating station includes at least two stages which operate simultaneously, each stage including punches and anvils and the punches and anvils of the first stage producing a first set of corrugations in a blank while the second stage produces a second set of corrugations in a blank previously operated on by the first stage, the apparatus including first transfer means for transferring blanks from the first stage to the second stage.
 5. Apparatus as claimed in claim 1 wherein a centre corrugation of the blank is formed first and the tools operate sequentially, outwardly from the centre corrugations to produce the remaining corrugations, the outer undeformed portions of the blank being free to move inwardly as the corrugations are formed.
 6. Apparatus as claimed in claim 1 further including a coining station operated by the movement of the movable platen of the press, the coining station receiving a corrugated blank from the corrugating station and compressing the corrugated blank laterally, at right angles to the corrugations, to form an unfinished laminated core, the apparatus including second transfer means for transferring corrugated blanks to the coining station.
 7. Apparatus as claimed in claim 6 wherein the coining station includes a pair of plungers which are slidable towards and away from one another between a pair of fixed parts, and said transfer means delivers the corrugated blank between said fixed parts and between said plungers, siad fixed parts resisting bowing of the corrugated blank out of the plane of the plungers as the plunger move toward one another to compress the corrugated blank.
 8. Apparatus as claimed in claim 7 wherein the coining station further includes stripping means which ensures that the unfinished core disengages from the plungers as the plungers move apart.
 9. Apparatus as claimed in claim 6, further including a sizing station, and third transfer means for transferring unfinished cores from the coining station to the sizing station where the unfinished cores are subject to sizing operation.
 10. Apparatus as claimed in claim 9 wherein the sizing station includes a sizing die through which the unfinished cores are passed.
 11. Apparatus as claimed in claim 10 wherein the force required to pass the cores through the sizing die is derived from the movement of the movable platen of the press.
 12. Apparatus as claimed in claim 9 wherein the sizing station includes indexing means operated by movement of the movable platen of the press for indexing unfinished cores through 90* from a position perpendicular to the direction of movement of the movable platen to a position in line with said direction of movement.
 13. Apparatus as claimed in claim 1 further including a blank forming station from which blanks are supplied to the corrugating station.
 14. Apparatus as claimed in claim 13 wherein the blank forming station receives a continuous strip of metal said strip being fed to the blank forming station in a step wise manner such that for each complete stroke of the press a length of strip equal in length to the length of tHe core to be produced is fed into the station.
 15. Apparatus as claimed in claim 13 wherein the blank forming station includes a slitting tool which for each stroke of the press produces the necessary slits in a length of strip which will constitute a single blank.
 16. Apparatus as claimed in claim 15 wherein the blank forming station further includes a planishing tool which for each stroke of the press planishes a previously slitted length of the strip.
 17. Apparatus as claimed in claim 16 wherein the blank forming station still further includes a guillotine which cuts previously slitted and planished lengths of strip to form blanks.
 18. Apparatus as claimed in claim 15 wherein the blank forming station includes a cropping tool which crops the edges of the incoming strip prior to the slitting operation, to ensure the width of the strip and therefore the width of the blanks to be formed is the desired width and to ensure that the edges of the strip are correctly orientated relative to the slitting tool.
 19. Apparatus as claimed in claim 13 including fourth transfer means for feeding blanks from the blank forming station to the corrugating station.
 20. Apparatus as claimed in claim 19 wherein said first, second and third, and fourth transfer means are part ofa movable carriage and operate simultaneously, said carriage being moved in conjunction with the movable platen of the press and being moved in a direction to feed components by an air spring which is compressed by the drive mechanism of the press to move the carriage in a return direction.
 21. Apparatus as claimed in claim 17 including fourth transfer means for feeding blanks from the blank forming station to the corrugating station.
 22. A method of manufacturing a laminated core, including the steps of supporting a sheet metal blank on a fixed anvil which comprises a pair of ribs of triangular cross section defining between them a V-shaped groove, the blank being supported with a slit therein aligned with the apex of the groove, moving a punch of triangular cross section towards the anvil so that the punch engages the blank along the line of said slit and deforms the blank into said groove to form a first corrugation, the uncorrugated portion of the blank being free to move inwardly as the corrugation is formed, moving a second punch of triangular cross section towards the blank along side the first punch and moving a second anvil of triangular cross section towards the first anvil, the second and first anvils when interengaged defining a second V-shaped groove parallel to said first V-shaped groove, the second punch bending the blank along the line of a second slit into said second V-shaped groove, as said second V-shaped groove is formed, to form a second corrugation in the blank, forming the required number of corrugations in the blank in similar manner, and compressing the corrugated blank transversely of the corrugations to collapse the blank so that the corrugations lie in facial contact.
 23. A method as claimed in claim 22 wherein as the second punch and second anvil are being moved to form the second corrugation, a third punch and a third anvil are moved to form a third corrugation on the opposite side of the first corrugation.
 24. A method as claimed in claim 22 wherein all of the corrugations with the exception of the first are produced in pairs, the corrugations of each pair being on opposite sides respectively of the central corrugation, and the corrugations being produced sequentially in a direction outwardly from the first corrugation.
 25. Apparatus for use in the manufacture of laminated cores for spark ignition system ignition coils, including a corrugating station which receives sheet metal blanks each of which has a plurality of parallel slits spaced apart by different distances dividing the blank into a plurality of laminae of different widths interconnected at their ends, the corrugating station including a movable platen movable relatively towards and away from a fixed platen, a plurality of punches of triangular cross section carried by the movable platen and moving therewith, resilient means urging the punches to predetermined positions relative to one another and to the movable platen, the punches being mounted for collapsing movement in the direction of the stroke of the movable platen in turn relative to one another and to the movable platen against the action of said resilient means during a single operating stroke of the movable platen so that the punches can collapse relative to one another in sequence during said single operating stroke, a plurality of anvils associated with said punches, and carried by the fixed platen, the anvil associated with the first punch of said plurality of punches being fixed, and comprising a pair of ribs of triangular cross section defining between them a V-shaped groove with which the first punch co-operates, and, the remaining anvils being of triangular cross-section, and being movable sequentially laterally with respect to the direction of movement of the movable platen towards the fixed anvil, to define further V-shaped grooves parallel to said first V-shaped groove and associated respectively with the remaining punches and, means operated by the movement of the movable platen causing movement of the movable anvils towards the fixed anvil in a sequential manner determined by the movement of the movable platen towards the fixed platen, so that the movement of the anvils is timed in a predetermined relation to the movement of the punches, the relative movement between the punches and the relative movement between the anvils, together with the relative movement of the punches with respect to the anvils causing a sequential formation of corrugations in said blank, with said slits of the blank at the apices of the corrugations. 